The present disclosure relates to the field of acquisition, processing, and display of tomosynthesis images and radiography images of an organ. More specifically, the present disclosure relates to a system and method for combined acquisition of tomosynthesis projection images and X-ray images and processing and display of combined imaging from these acquisitions.
Radiography is generally used for seeking abnormalities in an object of interest. A radiography image represents a projection of an object, for example an organ of a patient. In a more specific, nonlimiting, example, the organ is a breast and the images are mammographic images. Mammography has been used for decades for screening and diagnosing breast cancer. The radiography image is generally obtained by placing the object between a source emitting X-rays and a detector of X-rays, so that the X-rays attain the detector having crossed the object. The radiography image is then constructed from data provided by the detector and represents the object projected on the detector in the direction of the X-rays.
In the case of mammography, an experienced radiologist may distinguish radiological signs indicating a potential problem, for example microcalcification, masses, or other opacities. However, in a 2D projection image, super position of the tissues may hide lesions, but in no case is their actual position known in the object of interest, the practitioner not having any information on the position of the radiological sign in the projection direction.
Tomosynthesis is used in order to address these problems. In tomosynthesis a 3D representation of an organ may be obtained as a series of successive slices. The slices are reconstructed from projections of the object of interest under various angles. To do this, the object of interest is generally placed between a source emitting X-rays and a detector of X-rays. The source and/or the detector are mobile, so that the direction of projection of the object on the detector may vary (for example over an angular range of 30°). Several projections of the object of interest are thereby obtained under different angles, from which a three-dimensional representation of the object may be reconstructed, generally by a reconstruction method, for example as those known to one skilled in the art.
For each projection, the radiation doses of the X-rays are naturally less than those used for standard mammography. For example, by noting as D the radiation dose by standard mammography, and as N the number of projections used for tomosynthesis, the radiation dose used for each projection is generally of the order of D/N.
While both standard mammography and tomosynthesis are currently used by radiologists, each technique has advantages. Standard mammography forms better than tomosynthesis in imaging microcalcifications. This may be due to the higher energy and dose used to obtain any individual standard mammography image and also that the reconstruction process in tomosynthesis tends to blur edges of the already small calcifications. Tomosynthesis is superior in imaging of spiculated masses as the reconstruction in the tomosynthesis properly locates the mass within the organ as well as super position and back projection errors from objects of interest within the organ.
While radiologists may acquire both standard mammography and tomosynthesis images to leverage the advantages of each technique, these imaging processes are typically performed sequentially with the radiologist switching between the imaging techniques.
Rather, solutions that combine the acquisition, processing, and display of digital radiography and tomosynthesis can provide enhanced imaging solutions at the same or reduced radiation dose.